In the related art of vehicle seats, there is known an approach in which a rotary member is rotatably attached to a base member by a pin and is urged in a rotation direction by a spiral spring which is attached between the two members (see, JP-A-2008-80935). Specifically, the spiral spring is configured such that the central wound portion thereof is held by the pin, and one and the other ends thereof are held to the rotary member and the base member, respectively. Consequently, eccentric offset of the spiral spring attributable to twisting and inserting thereof is reduced since the spiral spring is pressed against the pin.